Method for forming a planar intermetal dielectric layer

Abstract

A method of forming a planar intermetal dielectric over conductive metal structures is disclosed. The method comprises the steps of: (1) forming a liner oxide layer over the conductive metal structures; (2) forming a spin on glass layer over the liner oxide layer; (3) forming a cap oxide layer over the spin on glass layer; (4) forming a TiN layer over the cap oxide layer; (5) patterning and etching a contact hole through the TiN layer using the cap oxide layer as an etching stop; and (6) etching the cap oxide, the spin on glass, and the liner oxide down to the conductive metal structures using the TiN layer as a mask.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A method of forming a planar intermetal dielectric over conductive metal structures, the method comprising the steps of: forming a liner oxide layer over the conductive metal structures;   forming a spin on glass layer over the liner oxide layer;   forming a cap oxide layer over the spin on glass layer;   forming a barrier layer over the cap oxide layer;   patterning and etching a contact hole through the barrier layer using the cap oxide layer as an etching stop; and   etching the cap oxide layer, the spin on glass layer, and the liner oxide layer down to the conductive metal structures using the barrier layer as a mask to form a via hole.   
     
     
       2. The method of claim 1 wherein said barrier layer is a barrier metal layer. 
     
     
       3. The method of claim 1 wherein said barrier layer is TiN. 
     
     
       4. The method of claim 1 wherein said barrier layer is Ti. 
     
     
       5. The method of claim 1 further including the step of depositing a further layer of TiN into said via hole. 
     
     
       6. The method of claim 5 further including the step of depositing a tungsten plug into said via hole. 
     
     
       7. The method of claim 1 wherein the thickness of said barrier layer is at least 300 angstroms. 
     
     
       8. The method of claim 1 wherein the step of patterning and etching said barrier layer includes the steps of: coating a photoresist layer onto said barrier layer;   exposing said photoresist layer to an exposing light through a reticle mask so as to remove a portion of the photoresist layer covering said contact hole;   developing said photoresist layer; etching said barrier layer using said photoresist layer as a mask; and stripping said photoresist layer.   
     
     
       9. A method of forming a via hole through to a conducting structure underlying an intermetal dielectric layer, said method comprising the steps of: forming an oxide layer over said conducting structure, wherein said oxide layer comprises a liner oxide layer, a spin on glass layer, and a cap oxide layer;   forming a barrier layer over said oxide layer;   patterning and etching said barrier layer to produce a contact hole in said barrier layer;   using said barrier layer as an etching mask, etching said oxide layer under said contact hole to reach said conducting structure to form said via hole.   
     
     
       10. The method of claim 9 wherein said barrier layer is a barrier metal layer. 
     
     
       11. The method of claim 9 wherein the thickness of said barrier layer is at least 300 angstroms. 
     
     
       12. The method of claim 9 wherein said barrier layer is TiN. 
     
     
       13. The method of claim 9 wherein said oxide layer comprises a liner oxide layer, an O 3  -TEOS oxide layer, and a cap oxide layer. 
     
     
       14. The method of claim 12 wherein said oxide layer comprises a liner oxide layer, an O 3  -TEOS oxide layer, and a cap oxide layer. 
     
     
       15. The method of claim 9 wherein said barrier layer is Ti. 
     
     
       16. The method of claim 9 wherein the step of patterning and etching said barrier layer includes the steps of: coating a photoresist layer onto said barrier layer;   exposing said photoresist layer to an exposing light through a reticle mask so as to remove a portion of the photoresist layer covering said contact hole;   developing said photoresist layer;   etching said barrier layer using said photoresist layer as a mask; and   stripping said photoresist layer.